TY - JOUR
T1 - Spectrum estimation of density operators with alkaline-earth atoms
Y1 - 2018
A1 - Michael E. Beverland
A1 - Jeongwan Haah
A1 - Gorjan Alagic
A1 - Gretchen K. Campbell
A1 - Ana Maria Rey
A1 - Alexey V. Gorshkov
AB - We show that Ramsey spectroscopy of fermionic alkaline-earth atoms in a square-well trap provides an efficient and accurate estimate for the eigenspectrum of a density matrix whose *n *copies are stored in the nuclear spins of *n *such atoms. This spectrum estimation is enabled by the high symmetry of the interaction Hamiltonian, dictated, in turn, by the decoupling of the nuclear spin from the electrons and by the shape of the square-well trap. Practical performance of this procedure and its potential applications to quantum computing, quantum simulation, and time-keeping with alkalineearth atoms are discussed.

VL - 120
UR - http://arxiv.org/abs/1608.02045
CP - 025301
U5 - https://doi.org/10.1103/PhysRevLett.120.025301
ER -
TY - JOUR
T1 - Steady-state superradiance with Rydberg polaritons
JF - arXiv:1611.00797
Y1 - 2016
A1 - Zhe-Xuan Gong
A1 - Minghui Xu
A1 - Michael Foss-Feig
A1 - James K. Thompson
A1 - Ana Maria Rey
A1 - Murray Holland
A1 - Alexey V. Gorshkov
AB - A steady-state superradiant laser can be used to generate ultranarrow-linewidth light, and thus has important applications in the fields of quantum information and precision metrology. However, the light produced by such a laser is still essentially classical. Here, we show that the introduction of a Rydberg medium into a cavity containing atoms with a narrow optical transition can lead to the steady-state superradiant emission of ultranarrow-linewidth nonclassical light. The cavity nonlinearity induced by the Rydberg medium strongly modifies the superradiance threshold, and leads to a Mollow triplet in the cavity output spectrum−this behavior can be understood as an unusual analogue of resonance fluorescence. The cavity output spectrum has an extremely sharp central peak, with a linewidth that can be far narrower than that of a classical superradiant laser. This unprecedented spectral sharpness, together with the nonclassical nature of the light, could lead to new applications in which spectrally pure quantum light is desired.

UR - https://arxiv.org/abs/1611.00797
ER -
TY - JOUR
T1 - Many-body dynamics of dipolar molecules in an optical lattice
JF - Physical Review Letters
Y1 - 2014
A1 - Kaden R. A. Hazzard
A1 - Bryce Gadway
A1 - Michael Foss-Feig
A1 - Bo Yan
A1 - Steven A. Moses
A1 - Jacob P. Covey
A1 - Norman Y. Yao
A1 - Mikhail D. Lukin
A1 - Jun Ye
A1 - Deborah S. Jin
A1 - Ana Maria Rey
AB - Understanding the many-body dynamics of isolated quantum systems is one of the central challenges in modern physics. To this end, the direct experimental realization of strongly correlated quantum systems allows one to gain insights into the emergence of complex phenomena. Such insights enable the development of theoretical tools that broaden our understanding. Here, we theoretically model and experimentally probe with Ramsey spectroscopy the quantum dynamics of disordered, dipolar-interacting, ultracold molecules in a partially filled optical lattice. We report the capability to control the dipolar interaction strength, and we demonstrate that the many-body dynamics extends well beyond a nearest-neighbor or mean-field picture, and cannot be quantitatively described using previously available theoretical tools. We develop a novel cluster expansion technique and demonstrate that our theoretical method accurately captures the measured dependence of the spin dynamics on molecule number and on the dipolar interaction strength. In the spirit of quantum simulation, this agreement simultaneously benchmarks the new theoretical method and verifies our microscopic understanding of the experiment. Our findings pave the way for numerous applications in quantum information science, metrology, and condensed matter physics.
VL - 113
UR - http://arxiv.org/abs/1402.2354v1
CP - 19
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.113.195302
ER -
TY - JOUR
T1 - Quantum correlations and entanglement in far-from-equilibrium spin systems
JF - Physical Review A
Y1 - 2014
A1 - Kaden R. A. Hazzard
A1 - Mauritz van den Worm
A1 - Michael Foss-Feig
A1 - Salvatore R. Manmana
A1 - Emanuele Dalla Torre
A1 - Tilman Pfau
A1 - Michael Kastner
A1 - Ana Maria Rey
AB - By applying complementary analytic and numerical methods, we investigate the dynamics of spin-$1/2$ XXZ models with variable-range interactions in arbitrary dimensions. The dynamics we consider is initiated from uncorrelated states that are easily prepared in experiments, and can be equivalently viewed as either Ramsey spectroscopy or a quantum quench. Our primary focus is the dynamical emergence of correlations and entanglement in these far-from-equilibrium interacting quantum systems: we characterize these correlations by the entanglement entropy, concurrence, and squeezing, which are inequivalent measures of entanglement corresponding to different quantum resources. In one spatial dimension, we show that the time evolution of correlation functions manifests a non-perturbative dynamic singularity. This singularity is characterized by a universal power-law exponent that is insensitive to small perturbations. Explicit realizations of these models in current experiments using polar molecules, trapped ions, Rydberg atoms, magnetic atoms, and alkaline-earth and alkali atoms in optical lattices, along with the relative merits and limitations of these different systems, are discussed.
VL - 90
UR - http://arxiv.org/abs/1406.0937v1
CP - 6
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.90.063622
ER -
TY - JOUR
T1 - Suppressing the loss of ultracold molecules via the continuous quantum Zeno effect
JF - Physical Review Letters
Y1 - 2014
A1 - Bihui Zhu
A1 - Bryce Gadway
A1 - Michael Foss-Feig
A1 - Johannes Schachenmayer
A1 - Michael Wall
A1 - Kaden R. A. Hazzard
A1 - Bo Yan
A1 - Steven A. Moses
A1 - Jacob P. Covey
A1 - Deborah S. Jin
A1 - Jun Ye
A1 - Murray Holland
A1 - Ana Maria Rey
AB - We investigate theoretically the suppression of two-body losses when the on-site loss rate is larger than all other energy scales in a lattice. This work quantitatively explains the recently observed suppression of chemical reactions between two rotational states of fermionic KRb molecules confined in one-dimensional tubes with a weak lattice along the tubes [Yan et al., Nature 501, 521-525 (2013)]. New loss rate measurements performed for different lattice parameters but under controlled initial conditions allow us to show that the loss suppression is a consequence of the combined effects of lattice confinement and the continuous quantum Zeno effect. A key finding, relevant for generic strongly reactive systems, is that while a single-band theory can qualitatively describe the data, a quantitative analysis must include multiband effects. Accounting for these effects reduces the inferred molecule filling fraction by a factor of five. A rate equation can describe much of the data, but to properly reproduce the loss dynamics with a fixed filling fraction for all lattice parameters we develop a mean-field model and benchmark it with numerically exact time-dependent density matrix renormalization group calculations.
VL - 112
UR - http://arxiv.org/abs/1310.2221v2
CP - 7
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.112.070404
ER -
TY - JOUR
T1 - Dynamical quantum correlations of Ising models on an arbitrary lattice and their resilience to decoherence
JF - New Journal of Physics
Y1 - 2013
A1 - Michael Foss-Feig
A1 - Kaden R A Hazzard
A1 - John J Bollinger
A1 - Ana Maria Rey
A1 - Charles W Clark
AB - Ising models, and the physical systems described by them, play a central role in generating entangled states for use in quantum metrology and quantum information. In particular, ultracold atomic gases, trapped ion systems, and Rydberg atoms realize long-ranged Ising models, which even in the absence of a transverse field can give rise to highly non-classical dynamics and long-range quantum correlations. In the first part of this paper, we present a detailed theoretical framework for studying the dynamics of such systems driven (at time t=0) into arbitrary unentangled non-equilibrium states, thus greatly extending and unifying the work of Ref. [1]. Specifically, we derive exact expressions for closed-time-path ordered correlation functions, and use these to study experimentally relevant observables, e.g. Bloch vector and spin-squeezing dynamics. In the second part, these correlation functions are then used to derive closed-form expressions for the dynamics of arbitrary spin-spin correlation functions in the presence of both T_1 (spontaneous spin relaxation/excitation) and T_2 (dephasing) type decoherence processes. Even though the decoherence is local, our solution reveals that the competition between Ising dynamics and T_1 decoherence gives rise to an emergent non-local dephasing effect, thereby drastically amplifying the degradation of quantum correlations. In addition to identifying the mechanism of this deleterious effect, our solution points toward a scheme to eliminate it via measurement-based coherent feedback.
VL - 15
U4 - 113008
UR - http://arxiv.org/abs/1306.0172v1
CP - 11
J1 - New J. Phys.
U5 - 10.1088/1367-2630/15/11/113008
ER -
TY - JOUR
T1 - Far from equilibrium quantum magnetism with ultracold polar molecules
JF - Physical Review Letters
Y1 - 2013
A1 - Kaden R. A. Hazzard
A1 - Salvatore R. Manmana
A1 - Michael Foss-Feig
A1 - Ana Maria Rey
AB - Recent theory has indicated how to emulate tunable models of quantum magnetism with ultracold polar molecules. Here we show that present molecule optical lattice experiments can accomplish three crucial goals for quantum emulation, despite currently being well below unit filling and not quantum degenerate. The first is to verify and benchmark the models proposed to describe these systems. The second is to prepare correlated and possibly useful states in well-understood regimes. The third is to explore many-body physics inaccessible to existing theoretical techniques. Our proposal relies on a non-equilibrium protocol that can be viewed either as Ramsey spectroscopy or an interaction quench. It uses only routine experimental tools available in any ultracold molecule experiment.
VL - 110
UR - http://arxiv.org/abs/1209.4076v1
CP - 7
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.110.075301
ER -
TY - JOUR
T1 - Kitaev honeycomb and other exotic spin models with polar molecules
JF - Molecular Physics
Y1 - 2013
A1 - Alexey V. Gorshkov
A1 - Kaden R. A. Hazzard
A1 - Ana Maria Rey
AB - We show that ultracold polar molecules pinned in an optical lattice can be used to access a variety of exotic spin models, including the Kitaev honeycomb model. Treating each molecule as a rigid rotor, we use DC electric and microwave fields to define superpositions of rotational levels as effective spin degrees of freedom, while dipole-dipole interactions give rise to interactions between the spins. In particular, we show that, with sufficient microwave control, the interaction between two spins can be written as a sum of five independently controllable Hamiltonian terms proportional to the five rank-2 spherical harmonics Y_{2,q}(theta,phi), where (theta,phi) are the spherical coordinates of the vector connecting the two molecules. To demonstrate the potential of this approach beyond the simplest examples studied in [S. R. Manmana et al., arXiv:1210.5518v2], we focus on the realization of the Kitaev honeycomb model, which can support exotic non-Abelian anyonic excitations. We also discuss the possibility of generating spin Hamiltonians with arbitrary spin S, including those exhibiting SU(N=2S+1) symmetry.
VL - 111
U4 - 1908 - 1916
UR - http://arxiv.org/abs/1301.5636v1
CP - 12-13
J1 - Molecular Physics
U5 - 10.1080/00268976.2013.800604
ER -
TY - JOUR
T1 - Non-equilibrium dynamics of Ising models with decoherence: an exact solution
JF - Physical Review A
Y1 - 2013
A1 - Michael Foss-Feig
A1 - Kaden R. A. Hazzard
A1 - John J. Bollinger
A1 - Ana Maria Rey
AB - The interplay between interactions and decoherence in many-body systems is of fundamental importance in quantum physics: Decoherence can degrade correlations, but can also give rise to a variety of rich dynamical and steady-state behaviors. We obtain an exact analytic solution for the non-equilibrium dynamics of Ising models with arbitrary interactions and subject to the most general form of local Markovian decoherence. Our solution shows that decoherence affects the relaxation of observables more than predicted by single-particle considerations. It also reveals a dynamical phase transition, specifically a Hopf bifurcation, which is absent at the single-particle level. These calculations are applicable to ongoing quantum information and emulation efforts using a variety of atomic, molecular, optical, and solid-state systems.
VL - 87
UR - http://arxiv.org/abs/1209.5795v2
CP - 4
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.87.042101
ER -
TY - JOUR
T1 - Topological phases in ultracold polar-molecule quantum magnets
JF - Physical Review B
Y1 - 2013
A1 - Salvatore R. Manmana
A1 - E. M. Stoudenmire
A1 - Kaden R. A. Hazzard
A1 - Ana Maria Rey
A1 - Alexey V. Gorshkov
AB - We show how to use polar molecules in an optical lattice to engineer quantum spin models with arbitrary spin S >= 1/2 and with interactions featuring a direction-dependent spin anisotropy. This is achieved by encoding the effective spin degrees of freedom in microwave-dressed rotational states of the molecules and by coupling the spins through dipolar interactions. We demonstrate how one of the experimentally most accessible anisotropies stabilizes symmetry protected topological phases in spin ladders. Using the numerically exact density matrix renormalization group method, we find that these interacting phases -- previously studied only in the nearest-neighbor case -- survive in the presence of long-range dipolar interactions. We also show how to use our approach to realize the bilinear-biquadratic spin-1 and the Kitaev honeycomb models. Experimental detection schemes and imperfections are discussed.
VL - 87
UR - http://arxiv.org/abs/1210.5518v2
CP - 8
J1 - Phys. Rev. B
U5 - 10.1103/PhysRevB.87.081106
ER -
TY - JOUR
T1 - Long-lived dipolar molecules and Feshbach molecules in a 3D optical lattice
JF - Physical Review Letters
Y1 - 2012
A1 - Amodsen Chotia
A1 - Brian Neyenhuis
A1 - Steven A. Moses
A1 - Bo Yan
A1 - Jacob P. Covey
A1 - Michael Foss-Feig
A1 - Ana Maria Rey
A1 - Deborah S. Jin
A1 - Jun Ye
AB - We have realized long-lived ground-state polar molecules in a 3D optical lattice, with a lifetime of up to 25 s, which is limited only by off-resonant scattering of the trapping light. Starting from a 2D optical lattice, we observe that the lifetime increases dramatically as a small lattice potential is added along the tube-shaped lattice traps. The 3D optical lattice also dramatically increases the lifetime for weakly bound Feshbach molecules. For a pure gas of Feshbach molecules, we observe a lifetime of >20 s in a 3D optical lattice; this represents a 100-fold improvement over previous results. This lifetime is also limited by off-resonant scattering, the rate of which is related to the size of the Feshbach molecule. Individually trapped Feshbach molecules in the 3D lattice can be converted to pairs of K and Rb atoms and back with nearly 100% efficiency.
VL - 108
UR - http://arxiv.org/abs/1110.4420v1
CP - 8
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.108.080405
ER -
TY - JOUR
T1 - Steady-state many-body entanglement of hot reactive fermions
JF - Physical Review Letters
Y1 - 2012
A1 - Michael Foss-Feig
A1 - Andrew J. Daley
A1 - James K. Thompson
A1 - Ana Maria Rey
AB - Entanglement is typically created via systematic intervention in the time evolution of an initially unentangled state, which can be achieved by coherent control, carefully tailored non-demolition measurements, or dissipation in the presence of properly engineered reservoirs. In this paper we show that two-component Fermi gases at ~\mu K temperatures naturally evolve, in the presence of reactive two-body collisions, into states with highly entangled (Dicke-type) spin wavefunctions. The entanglement is a steady-state property that emerges---without any intervention---from uncorrelated initial states, and could be used to improve the accuracy of spectroscopy in experiments with fermionic alkaline earth atoms or fermionic groundstate molecules.
VL - 109
UR - http://arxiv.org/abs/1207.4741v1
CP - 23
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.109.230501
ER -
TY - JOUR
T1 - d-Wave Superfluidity in Optical Lattices of Ultracold Polar Molecules
JF - Physical Review A
Y1 - 2011
A1 - Kevin A. Kuns
A1 - Ana Maria Rey
A1 - Alexey V. Gorshkov
AB - Recent work on ultracold polar molecules, governed by a generalization of the t-J Hamiltonian, suggests that molecules may be better suited than atoms for studying d-wave superfluidity due to stronger interactions and larger tunability of the system. We compute the phase diagram for polar molecules in a checkerboard lattice consisting of weakly coupled square plaquettes. In the simplest experimentally realizable case where there is only tunneling and an XX-type spin-spin interaction, we identify the parameter regime where d-wave superfluidity occurs. We also find that the inclusion of a density-density interaction destroys the superfluid phase and that the inclusion of a spin-density or an Ising-type spin-spin interaction can enhance the superfluid phase. We also propose schemes for experimentally realizing the perturbative calculations exhibiting enhanced d-wave superfluidity.
VL - 84
UR - http://arxiv.org/abs/1110.5330v2
CP - 6
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.84.063639
ER -
TY - JOUR
T1 - Phase diagram of the Bose Kondo-Hubbard model
JF - Physical Review A
Y1 - 2011
A1 - Michael Foss-Feig
A1 - Ana Maria Rey
AB - We study a bosonic version of the Kondo lattice model with an on-site repulsion in the conduction band, implemented with alkali atoms in two bands of an optical lattice. Using both weak and strong-coupling perturbation theory, we find that at unit filling of the conduction bosons the superfluid to Mott insulator transition should be accompanied by a magnetic transition from a ferromagnet (in the superfluid) to a paramagnet (in the Mott insulator). Furthermore, an analytic treatment of Gutzwiller mean-field theory reveals that quantum spin fluctuations induced by the Kondo exchange cause the otherwise continuous superfluid to Mott-insulator phase transition to be first order. We show that lattice separability imposes a serious constraint on proposals to exploit excited bands for quantum simulations, and discuss a way to overcome this constraint in the context of our model by using an experimentally realized non-separable lattice. A method to probe the first-order nature of the transition based on collapses and revivals of the matter-wave field is also discussed.
VL - 84
UR - http://arxiv.org/abs/1103.0245v2
CP - 5
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.84.053619
ER -
TY - JOUR
T1 - Quantum Magnetism with Polar Alkali Dimers
JF - Physical Review A
Y1 - 2011
A1 - Alexey V. Gorshkov
A1 - Salvatore R. Manmana
A1 - Gang Chen
A1 - Eugene Demler
A1 - Mikhail D. Lukin
A1 - Ana Maria Rey
AB - We show that dipolar interactions between ultracold polar alkali dimers in optical lattices can be used to realize a highly tunable generalization of the t-J model, which we refer to as the t-J-V-W model. The model features long-range spin-spin interactions J_z and J_perp of XXZ type, long-range density-density interaction V, and long-range density-spin interaction W, all of which can be controlled in both magnitude and sign independently of each other and of the tunneling t. The "spin" is encoded in the rotational degree of freedom of the molecules, while the interactions are controlled by applied static electric and continuous-wave microwave fields. Furthermore, we show that nuclear spins of the molecules can be used to implement an additional (orbital) degree of freedom that is coupled to the original rotational degree of freedom in a tunable way. The presented system is expected to exhibit exotic physics and to provide insights into strongly correlated phenomena in condensed matter systems. Realistic experimental imperfections are discussed.
VL - 84
UR - http://arxiv.org/abs/1106.1655v1
CP - 3
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.84.033619
ER -
TY - JOUR
T1 - Resolved atomic interaction sidebands in an optical clock transition
JF - Physical Review Letters
Y1 - 2011
A1 - Michael Bishof
A1 - Yige Lin
A1 - Matthew D. Swallows
A1 - Alexey V. Gorshkov
A1 - Jun Ye
A1 - Ana Maria Rey
AB - We report the observation of resolved atomic interaction sidebands (ISB) in the ${}^{87}$Sr optical clock transition when atoms at microkelvin temperatures are confined in a two-dimensional (2D) optical lattice. The ISB are a manifestation of the strong interactions that occur between atoms confined in a quasi-one-dimensional geometry and disappear when the confinement is relaxed along one dimension. The emergence of ISB is linked to the recently observed suppression of collisional frequency shifts in [1]. At the current temperatures, the ISB can be resolved but are broad. At lower temperatures, ISB are predicted to be substantially narrower and usable as powerful spectroscopic tools in strongly interacting alkaline-earth gases.
VL - 106
UR - http://arxiv.org/abs/1102.1016v2
CP - 25
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.106.250801
ER -
TY - JOUR
T1 - Spectroscopy of dipolar fermions in 2D pancakes and 3D lattices
JF - Physical Review A
Y1 - 2011
A1 - Kaden R. A. Hazzard
A1 - Alexey V. Gorshkov
A1 - Ana Maria Rey
AB - Motivated by ongoing measurements at JILA, we calculate the recoil-free spectra of dipolar interacting fermions, for example ultracold heteronuclear molecules, in a one-dimensional lattice of two-dimensional pancakes, spectroscopically probing transitions between different internal (e.g., rotational) states. We additionally incorporate p-wave interactions and losses, which are important for reactive molecules such as KRb. Moreover, we consider other sources of spectral broadening: interaction-induced quasiparticle lifetimes and the different polarizabilities of the different rotational states used for the spectroscopy. Although our main focus is molecules, some of the calculations are also useful for optical lattice atomic clocks. For example, understanding the p-wave shifts between identical fermions and small dipolar interactions coming from the excited clock state are necessary to reach future precision goals. Finally, we consider the spectra in a deep 3D lattice and show how they give a great deal of information about static correlation functions, including \textit{all} the moments of the density correlations between nearby sites. The range of correlations measurable depends on spectroscopic resolution and the dipole moment.
VL - 84
UR - http://arxiv.org/abs/1106.1718v1
CP - 3
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.84.033608
ER -
TY - JOUR
T1 - Tunable Superfluidity and Quantum Magnetism with Ultracold Polar Molecules
JF - Physical Review Letters
Y1 - 2011
A1 - Alexey V. Gorshkov
A1 - Salvatore R. Manmana
A1 - Gang Chen
A1 - Jun Ye
A1 - Eugene Demler
A1 - Mikhail D. Lukin
A1 - Ana Maria Rey
AB - By selecting two dressed rotational states of ultracold polar molecules in an optical lattice, we obtain a highly tunable generalization of the t-J model, which we refer to as the t-J-V-W model. In addition to XXZ spin exchange, the model features density-density interactions and novel density-spin interactions; all interactions are dipolar. We show that full control of all interaction parameters in both magnitude and sign can be achieved independently of each other and of the tunneling. As a first step towards demonstrating the potential of the system, we apply the density matrix renormalization group method (DMRG) to obtain the 1D phase diagram of the simplest experimentally realizable case. Specifically, we show that the tunability and the long-range nature of the interactions in the t-J-V-W model enable enhanced superfluidity. Finally, we show that Bloch oscillations in a tilted lattice can be used to probe the phase diagram experimentally.
VL - 107
UR - http://arxiv.org/abs/1106.1644v1
CP - 11
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.107.115301
ER -
TY - JOUR
T1 - Heavy fermions in an optical lattice
JF - Physical Review A
Y1 - 2010
A1 - Michael Foss-Feig
A1 - Michael Hermele
A1 - Victor Gurarie
A1 - Ana Maria Rey
AB - We employ a mean-field theory to study ground-state properties and transport of a two-dimensional gas of ultracold alklaline-earth metal atoms governed by the Kondo Lattice Hamiltonian plus a parabolic confining potential. In a homogenous system this mean-field theory is believed to give a qualitatively correct description of heavy fermion metals and Kondo insulators: it reproduces the Kondo-like scaling of the quasiparticle mass in the former, and the same scaling of the excitation gap in the latter. In order to understand ground-state properties in a trap we extend this mean-field theory via local-density approximation. We find that the Kondo insulator gap manifests as a shell structure in the trapped density profile. In addition, a strong signature of the large Fermi surface expected for heavy fermion systems survives the confinement, and could be probed in time-of-flight experiments. From a full self-consistent diagonalization of the mean-field theory we are able to study dynamics in the trap. We find that the mass enhancement of quasiparticle excitations in the heavy Fermi liquid phase manifests as slowing of the dipole oscillations that result from a sudden displacement of the trap center.
VL - 82
UR - http://arxiv.org/abs/1007.5083v1
CP - 5
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.82.053624
ER -
TY - JOUR
T1 - Probing the Kondo Lattice Model with Alkaline Earth Atoms
JF - Physical Review A
Y1 - 2010
A1 - Michael Foss-Feig
A1 - Michael Hermele
A1 - Ana Maria Rey
AB - We study transport properties of alkaline-earth atoms governed by the Kondo Lattice Hamiltonian plus a harmonic confining potential, and suggest simple dynamical probes of several different regimes of the phase diagram that can be implemented with current experimental techniques. In particular, we show how Kondo physics at strong coupling, low density, and in the heavy fermion phase is manifest in the dipole oscillations of the conduction band upon displacement of the trap center.
VL - 81
UR - http://arxiv.org/abs/0912.4762v1
CP - 5
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.81.051603
ER -
TY - JOUR
T1 - Alkaline-Earth-Metal Atoms as Few-Qubit Quantum Registers
JF - Physical Review Letters
Y1 - 2009
A1 - Alexey V. Gorshkov
A1 - Ana Maria Rey
A1 - Andrew J. Daley
A1 - Martin M. Boyd
A1 - Jun Ye
A1 - Peter Zoller
A1 - Mikhail D. Lukin
AB - We propose and analyze a novel approach to quantum information processing, in which multiple qubits can be encoded and manipulated using electronic and nuclear degrees of freedom associated with individual alkaline-earth atoms trapped in an optical lattice. Specifically, we describe how the qubits within each register can be individually manipulated and measured with sub-wavelength optical resolution. We also show how such few-qubit registers can be coupled to each other in optical superlattices via conditional tunneling to form a scalable quantum network. Finally, potential applications to quantum computation and precision measurements are discussed.
VL - 102
UR - http://arxiv.org/abs/0812.3660v2
CP - 11
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.102.110503
ER -
TY - JOUR
T1 - Mean-field treatment of the damping of the oscillations of a 1D Bose gas in an optical lattice
JF - Physical Review A
Y1 - 2006
A1 - Julio Gea-Banacloche
A1 - Ana Maria Rey
A1 - Guido Pupillo
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - We present a theoretical treatment of the surprisingly large damping observed recently in one-dimensional Bose-Einstein atomic condensates in optical lattices. We show that time-dependent Hartree-Fock-Bogoliubov (HFB) calculations can describe qualitatively the main features of the damping observed over a range of lattice depths. We also derive a formula of the fluctuation-dissipation type for the damping, based on a picture in which the coherent motion of the condensate atoms is disrupted as they try to flow through the random local potential created by the irregular motion of noncondensate atoms. We expect this irregular motion to result from the well-known dynamical instability exhibited by the mean-field theory for these systems. When parameters for the characteristic strength and correlation times of the fluctuations, obtained from the HFB calculations, are substituted in the damping formula, we find very good agreement with the experimentally-observed damping, as long as the lattice is shallow enough for the fraction of atoms in the Mott insulator phase to be negligible. We also include, for completeness, the results of other calculations based on the Gutzwiller ansatz, which appear to work better for the deeper lattices.
VL - 73
UR - http://arxiv.org/abs/cond-mat/0410677v4
CP - 1
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.73.013605
ER -
TY - JOUR
T1 - Pseudo-fermionization of 1-D bosons in optical lattices
JF - New Journal of Physics
Y1 - 2006
A1 - Guido Pupillo
A1 - Ana Maria Rey
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - We present a model that generalizes the Bose-Fermi mapping for strongly correlated 1D bosons in an optical lattice, to cases in which the average number of atoms per site is larger than one. This model gives an accurate account of equilibrium properties of such systems, in parameter regimes relevant to current experiments. The application of this model to non-equilibrium phenomena is explored by a study of the dynamics of an atom cloud subject to a sudden displacement of the confining potential. Good agreement is found with results of recent experiments. The simplicity and intuitive appeal of this model make it attractive as a general tool for understanding bosonic systems in the strongly correlated regime.
VL - 8
U4 - 161 - 161
UR - http://arxiv.org/abs/cond-mat/0505325v2
CP - 8
J1 - New J. Phys.
U5 - 10.1088/1367-2630/8/8/161
ER -
TY - JOUR
T1 - Bragg Spectroscopy of ultracold atoms loaded in an optical lattice
JF - Physical Review A
Y1 - 2005
A1 - Ana Maria Rey
A1 - P. Blair Blakie
A1 - Guido Pupillo
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - We study Bragg spectroscopy of ultra-cold atoms in one-dimensional optical lattices as a method for probing the excitation spectrum in the Mott insulator phase, in particular the one particle-hole excitation band. Within the framework of perturbation theory we obtain an analytical expression for the dynamic structure factor $S(q,\omega)$ and use it to calculate the imparted energy which has shown to be a relevant observable in recent experiments. We test the accuracy of our approximations by comparing them with numerically exact solutions of the Bose-Hubbard model in restricted cases and establish the limits of validity of our linear response analysis. Finally we show that when the system is deep in the Mott insulator regime, its response to the Bragg perturbation is temperature dependent. We suggest that this dependence might be used as a tool to probe temperatures of order of the Mott gap.
VL - 72
UR - http://arxiv.org/abs/cond-mat/0406552v2
CP - 2
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.72.023407
ER -
TY - JOUR
T1 - Scalable register initialization for quantum computing in an optical lattice
JF - Journal of Physics B: Atomic, Molecular and Optical Physics
Y1 - 2005
A1 - Gavin K. Brennen
A1 - Guido Pupillo
A1 - Ana Maria Rey
A1 - Charles W. Clark
A1 - Carl J. Williams
AB - The Mott insulator state created by loading an atomic Bose-Einstein condensate (BEC) into an optical lattice may be used as a means to prepare a register of atomic qubits in a quantum computer. Such architecture requires a lattice commensurately filled with atoms, which corresponds to the insulator state only in the limit of zero inter-well tunneling. We show that a lattice with spatial inhomogeneity created by a quadratic magnetic trapping potential can be used to isolate a subspace in the center which is impervious to hole-hoping. Components of the wavefunction with more than one atom in any well can be projected out by selective measurement on a molecular photo-associative transition. Maintaining the molecular coupling induces a quantum Zeno effect that can sustain a commensurately filled register for the duration of a quantum computation.
VL - 38
U4 - 1687 - 1694
UR - http://arxiv.org/abs/quant-ph/0312069v1
CP - 11
J1 - J. Phys. B: At. Mol. Opt. Phys.
U5 - 10.1088/0953-4075/38/11/010
ER -
TY - JOUR
T1 - Ultracold atoms confined in an optical lattice plus parabolic potential: a closed-form approach
JF - Physical Review A
Y1 - 2005
A1 - Ana Maria Rey
A1 - Guido Pupillo
A1 - Charles W. Clark
A1 - Carl J. Williams
AB - We discuss interacting and non-interacting one dimensional atomic systems trapped in an optical lattice plus a parabolic potential. We show that, in the tight-binding approximation, the non-interacting problem is exactly solvable in terms of Mathieu functions. We use the analytic solutions to study the collective oscillations of ideal bosonic and fermionic ensembles induced by small displacements of the parabolic potential. We treat the interacting boson problem by numerical diagonalization of the Bose-Hubbard Hamiltonian. From analysis of the dependence upon lattice depth of the low-energy excitation spectrum of the interacting system, we consider the problems of "fermionization" of a Bose gas, and the superfluid-Mott insulator transition. The spectrum of the noninteracting system turns out to provide a useful guide to understanding the collective oscillations of the interacting system, throughout a large and experimentally relevant parameter regime.
VL - 72
UR - http://arxiv.org/abs/cond-mat/0503477v2
CP - 3
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.72.033616
ER -
TY - JOUR
T1 - Scalable quantum computation in systems with Bose-Hubbard dynamics
JF - Journal of Modern Optics
Y1 - 2004
A1 - Guido Pupillo
A1 - Ana Maria Rey
A1 - Gavin Brennen
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - Several proposals for quantum computation utilize a lattice type architecture with qubits trapped by a periodic potential. For systems undergoing many body interactions described by the Bose-Hubbard Hamiltonian, the ground state of the system carries number fluctuations that scale with the number of qubits. This process degrades the initialization of the quantum computer register and can introduce errors during error correction. In an earlier manuscript we proposed a solution to this problem tailored to the loading of cold atoms into an optical lattice via the Mott Insulator phase transition. It was shown that by adding an inhomogeneity to the lattice and performing a continuous measurement, the unit filled state suitable for a quantum computer register can be maintained. Here, we give a more rigorous derivation of the register fidelity in homogeneous and inhomogeneous lattices and provide evidence that the protocol is effective in the finite temperature regime.
VL - 51
U4 - 2395 - 2404
UR - http://arxiv.org/abs/quant-ph/0403052v2
CP - 16-18
J1 - Journal of Modern Optics
U5 - 10.1080/09500340408231798
ER -
TY - JOUR
T1 - Bogoliubov approach to superfluidity of atoms in an optical lattice
JF - Journal of Physics B: Atomic, Molecular and Optical Physics
Y1 - 2003
A1 - Ana Maria Rey
A1 - Keith Burnett
A1 - Robert Roth
A1 - Mark Edwards
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - We use the Bogoliubov theory of atoms in an optical lattice to study the approach to the Mott-insulator transition. We derive an explicit expression for the superfluid density based on the rigidity of the system under phase variations. This enables us to explore the connection between the quantum depletion of the condensate and the quasi-momentum distribution on the one hand and the superfluid fraction on the other. The approach to the insulator phase may be characterized through the filling of the band by quantum depletion, which should be directly observable via the matter wave interference patterns. We complement these findings by self-consistent Hartree-Fock-Bogoliubov-Popov calculations for one-dimensional lattices including the effects of a parabolic trapping potential.
VL - 36
U4 - 825 - 841
UR - http://arxiv.org/abs/cond-mat/0210550v2
CP - 5
J1 - J. Phys. B: At. Mol. Opt. Phys.
U5 - 10.1088/0953-4075/36/5/304
ER -